see also http://nnsa.energy.gov/aboutus/ouroperations/generalcounsel/foia/reading-room-after2000?page=21
Note the "Confetti argument" section where legendary Los Alamos National Laboratory Director Howard Agnew (the man who personally filmed the Hiroshima explosion using a cine camera in a B29) points out that the effects of Hiroshima on substantial buildings was NOT impressive. For a detailed discussion, please see http://glasstone.blogspot.co.uk/2015/07/capabilities-of-nuclear-weapons.html
Other warhead histories by Betty Perkins include LA-13755-H: Tracing the Origins of the Modern Primary: 1952-1970 (U) , LA-12950-H: Why Nougat? (U) Understanding the Events Leading to the Los Alamos Scientific Laboratory's First Full-Scale Underground Test Series and Related Considerations (U), and LA-12393-H: The 1959-1961 TA-49 Experiments and Related Considerations (U).